1 files changed, 262 insertions, 0 deletions
diff --git a/src/live_effects/lpe-powerstroke.cpp b/src/live_effects/lpe-powerstroke.cpp
new file mode 100644
index 000000000..6109ea498
--- /dev/null
+++ b/src/live_effects/lpe-powerstroke.cpp
@@ -0,0 +1,262 @@
+#define INKSCAPE_LPE_POWERSTROKE_CPP
+/** \file
+ * @brief  PowerStroke LPE implementation. Creates curves with modifiable stroke width.
+ */
+/* Authors:
+ *   Johan Engelen <j.b.c.engelen@utwente.nl>
+ *
+ * Copyright (C) 2010 Authors
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#include "live_effects/lpe-powerstroke.h"
+
+#include "sp-shape.h"
+#include "display/curve.h"
+
+#include <2geom/path.h>
+#include <2geom/piecewise.h>
+#include <2geom/sbasis-geometric.h>
+#include <2geom/transforms.h>
+#include <2geom/bezier-utils.h>
+
+
+/// @TODO  Move this to 2geom
+namespace Geom {
+namespace Interpolate {
+
+class Interpolator {
+public:
+    Interpolator() {};
+    virtual ~Interpolator() {};
+
+//    virtual Piecewise<D2<SBasis> > interpolateToPwD2Sb(std::vector<Point> points) = 0;
+    virtual Path interpolateToPath(std::vector<Point> points) = 0;
+
+private:
+    Interpolator(const Interpolator&);
+    Interpolator& operator=(const Interpolator&);
+};
+
+class Linear : public Interpolator {
+public:
+    Linear() {};
+    virtual ~Linear() {};
+
+    virtual Path interpolateToPath(std::vector<Point> points) {
+        Path path;
+        path.start( points.at(0) );
+        for (unsigned int i = 1 ; i < points.size(); ++i) {
+            path.appendNew<Geom::LineSegment>(points.at(i));
+        }
+        return path;
+    };
+
+private:
+    Linear(const Linear&);
+    Linear& operator=(const Linear&);
+};
+
+// this class is terrible
+class CubicBezierFit : public Interpolator {
+public:
+    CubicBezierFit() {};
+    virtual ~CubicBezierFit() {};
+
+    virtual Path interpolateToPath(std::vector<Point> points) {
+        unsigned int n_points = points.size();
+        // worst case gives us 2 segment per point
+        int max_segs = 8*n_points;
+        Geom::Point * b = g_new(Geom::Point, max_segs);
+        Geom::Point * points_array = g_new(Geom::Point, 4*n_points);
+        for (unsigned i = 0; i < n_points; ++i) {
+            points_array[i] = points.at(i);
+        }
+
+        double tolerance_sq = 0; // this value is just a random guess
+
+        int const n_segs = Geom::bezier_fit_cubic_r(b, points_array, n_points,
+                                                 tolerance_sq, max_segs);
+
+        Geom::Path fit;
+        if ( n_segs > 0)
+        {
+            fit.start(b[0]);
+            for (int c = 0; c < n_segs; c++) {
+                fit.appendNew<Geom::CubicBezier>(b[4*c+1], b[4*c+2], b[4*c+3]);
+            }
+        }
+        g_free(b);
+        g_free(points_array);
+        return fit;
+    };
+
+private:
+    CubicBezierFit(const CubicBezierFit&);
+    CubicBezierFit& operator=(const CubicBezierFit&);
+};
+
+/// @todo invent name for this class
+class CubicBezierJohan : public Interpolator {
+public:
+    CubicBezierJohan() {};
+    virtual ~CubicBezierJohan() {};
+
+    virtual Path interpolateToPath(std::vector<Point> points) {
+        Path fit;
+        fit.start(points.at(0));
+        for (unsigned int i = 1; i < points.size(); ++i) {
+            Point p0 = points.at(i-1);
+            Point p1 = points.at(i);
+            Point dx = Point(p1[X] - p0[X], 0);
+            fit.appendNew<CubicBezier>(p0+0.2*dx, p1-0.2*dx, p1);
+        }
+        return fit;
+    };
+
+private:
+    CubicBezierJohan(const CubicBezierJohan&);
+    CubicBezierJohan& operator=(const CubicBezierJohan&);
+};
+
+} //namespace Interpolate
+} //namespace Geom
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+LPEPowerStroke::LPEPowerStroke(LivePathEffectObject *lpeobject) :
+    Effect(lpeobject),
+    offset_points(_("Offset points"), _("Offset points"), "offset_points", &wr, this),
+    sort_points(_("Sort points"), _("Sort offset points according to their time value along the curve."), "sort_points", &wr, this, true)
+{
+    show_orig_path = true;
+
+    /// @todo offset_points are initialized with empty path, is that bug-save?
+
+    registerParameter( dynamic_cast<Parameter *>(&offset_points) );
+    registerParameter( dynamic_cast<Parameter *>(&sort_points) );
+}
+
+LPEPowerStroke::~LPEPowerStroke()
+{
+
+}
+
+
+void
+LPEPowerStroke::doOnApply(SPLPEItem *lpeitem)
+{
+    std::vector<Geom::Point> points;
+    Geom::Path::size_type size = SP_SHAPE(lpeitem)->curve->get_pathvector().front().size_open();
+    points.push_back( Geom::Point(0,0) );
+    points.push_back( Geom::Point(0.5*size,0) );
+    points.push_back( Geom::Point(size,0) );
+    offset_points.param_set_and_write_new_value(points);
+}
+
+static bool compare_offsets (Geom::Point first, Geom::Point second)
+{
+    return first[Geom::X] < second[Geom::X];
+}
+
+
+Geom::Piecewise<Geom::D2<Geom::SBasis> >
+LPEPowerStroke::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
+{
+    using namespace Geom;
+
+    offset_points.set_pwd2(pwd2_in);
+
+    Piecewise<D2<SBasis> > der = unitVector(derivative(pwd2_in));
+    Piecewise<D2<SBasis> > n = rot90(der);
+    offset_points.set_pwd2_normal(n);
+
+        // see if we should treat the path as being closed.
+    bool closed_path = false;
+    if ( are_near(pwd2_in.firstValue(), pwd2_in.lastValue()) ) {
+        closed_path = true;
+    }
+
+    Piecewise<D2<SBasis> > output;
+    if (!closed_path) {
+        // perhaps use std::list instead of std::vector?
+        std::vector<Geom::Point> ts(offset_points.data().size() + 2);
+        // first and last point coincide with input path (for now at least)
+        ts.front() = Point(pwd2_in.domain().min(),0);
+        ts.back()  = Point(pwd2_in.domain().max(),0);
+        for (unsigned int i = 0; i < offset_points.data().size(); ++i) {
+            ts.at(i+1) = offset_points.data().at(i);
+        }
+
+        if (sort_points) {
+            sort(ts.begin(), ts.end(), compare_offsets);
+        }
+
+        // create stroke path where points (x,y) := (t, offset)
+        Geom::Interpolate::CubicBezierJohan interpolator;
+        Path strokepath = interpolator.interpolateToPath(ts);
+        Path mirroredpath = strokepath.reverse() * Geom::Scale(1,-1);
+
+        strokepath.append(mirroredpath, Geom::Path::STITCH_DISCONTINUOUS);
+        strokepath.close();
+
+        D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(strokepath.toPwSb());
+        Piecewise<SBasis> x = Piecewise<SBasis>(patternd2[0]);
+        Piecewise<SBasis> y = Piecewise<SBasis>(patternd2[1]);
+
+        output = compose(pwd2_in,x) + y*compose(n,x);
+    } else {
+        // path is closed
+
+        // perhaps use std::list instead of std::vector?
+        std::vector<Geom::Point> ts = offset_points.data();
+        if (sort_points) {
+            sort(ts.begin(), ts.end(), compare_offsets);
+        }
+        // add extra points for interpolation between first and last point
+        Point first_point = ts.front();
+        Point last_point = ts.back();
+        ts.insert(ts.begin(), last_point - Point(pwd2_in.domain().extent() ,0));
+        ts.push_back( first_point + Point(pwd2_in.domain().extent() ,0) );
+        // create stroke path where points (x,y) := (t, offset)
+        Geom::Interpolate::CubicBezierJohan interpolator;
+        Path strokepath = interpolator.interpolateToPath(ts);
+
+        // output 2 separate paths
+        D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(strokepath.toPwSb());
+        Piecewise<SBasis> x = Piecewise<SBasis>(patternd2[0]);
+        Piecewise<SBasis> y = Piecewise<SBasis>(patternd2[1]);
+        // find time values for which x lies outside path domain
+        // and only take portion of x and y that lies within those time values
+        std::vector< double > rtsmin = roots (x - pwd2_in.domain().min());
+        std::vector< double > rtsmax = roots (x - pwd2_in.domain().max());
+        if ( !rtsmin.empty() && !rtsmax.empty() ) {
+            x = portion(x, rtsmin.at(0), rtsmax.at(0));
+            y = portion(y, rtsmin.at(0), rtsmax.at(0));
+        }
+        output = compose(pwd2_in,x) + y*compose(n,x);
+        x = reverse(x);
+        y = reverse(y);
+        output.concat(compose(pwd2_in,x) - y*compose(n,x));
+    }
+
+    return output;
+}
+
+/* ######################## */
+
+} //namespace LivePathEffect
+} /* namespace Inkscape */
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :